Conventional lubricant deterioration sensors detect a red-green-blue (RGB) absorbance in visible light that travels through lubricant and then detect a deterioration degree of the lubricant based on the detected RGB absorbance (see, for example, Patent Literature 1).
The lubricant deterioration sensor disclosed in Patent Literature 1 includes a space where lubricant flows in, an LED that emits a visible light beam toward the space, and an RGB sensor that receives a light beam that is emitted from the LED and traveled through the space. In the lubricant deterioration sensor, the LED emits a light beam and the RGB sensor receives the light beam. A result of detection performed by the RGB sensor is output to an external device. The conventional lubricant deterioration sensor does not perform adjustment of its detection accuracy and determination